Despite massive press efforts to conflate them, there are two separate efforts in play between President Trump and the Ukraine. First, there is a request for cooperation with a Dept of Justice investigation of the Intelligence Services involvement in the counterintelligence effort mounted against the Trump campaign under US Attorney John Durham. Then there is opposition research conducted by Rudy Giuliani directed more toward the conflicts of interest regarding Joen and Hunter Biden.
Both are entirely legal, but while making US aid contingent on cooperation in the official investigation would be standard practice, cooperation with Giuliani’s research must be voluntary. There is nothing in the transcript of the phone call, nor any other documentation we have seen so far to indicate that line was crossed.